QDs Capped with Enterovirus As Imaging Probes for Drug Screening

Abstract

The increasing threats of viral diseases have gained worldwide attention in recent years. Quite a few infectious diseases are still lack of effective prevention or treatment. The pace of developing antiviral agents could be expedited by the availability of quick and efficient drug screening platforms. Enterovirus 71 (EV71) is a highly infectious major causative agent of hand, foot, and mouth disease (HFMD) which could lead to severe neurological complications. There is currently no effective therapy against EV71. In this study, quantum dot (QD), an emerging probe for biological imaging and medical diagnostics, was employed to form complexes with virus and used as fluorescent imaging probes for exploring potential antiviral therapeutics. Inorganic CdSe/ZnS QDs synthesized in organic phase were encapsulated by amphiphilic alginate to attain biocompatible water-soluble QDs via phase transfer. To construct a QD-virus imaging modality capable of providing meaningful information, preservation of viral infectivity after tagging EV71 with QDs is of utmost importance. In order to form colloidal complexes of QD-virus, electrostatic repulsion force generated from both negatively-charged EV71 and QDs was neutralized by various concentrations of cationic polybrene. Results showed that BHK-21 cells infected with EV71 incorporated with QDs exhibited bright fluorescence intracellularly within 30 min. To demonstrate the potency of QD-virus complexes as bioprobes for screening antiviral agents, BHK-21 cells were incubated for one hour with allophycocyanin (APC), C-phycocyanin (CPC) purified from blue-green algae and then infected with QD-virus complexes. Based on the developed cellbased imaging assay, APC and CPC with concentration of 31.25 μg/mL led to extremely weak intracellular fluorescence post-infection of QD/virus complexes for 60 min. That is, the efficacy of anti-enteroviral activity of the algae extract was clearly illustrated by the inorganic-organic hybrid platform constructed in current study. © International Federation of Medical and Biological Engineering 2009.